One thing to note while looking at the blueprint is the inclusion of a VGA connector. Is Microsoft trying to get PC gamers to take a liking to the Xbox? Since a regular television (which over 99% of people have) can only display low resolutions, it looks like MS wants to show off the console's high-res capabilities.
And four USB ports? Most PCs don't even have that many. Microsoft may be pushing some peripherals that might be "taboo" for console gamers. Since it will feature a hard drive (probably provided by Seagate) and an expansion for a larger one, don't be surprised if you could hook up a digital camera or other PC toys to this nifty little box.
Everyone should take this blueprint with a grain of salt. First, this is most likely just a prototype. Blueprints like this are meant to design where device locations may go. And obviously, it doesn't show how this machine will actually look. Rumors are that the Xbox will come in not one, but a few "flavors," including chrome, black, and neon.